DS2778 Maxim Integrated Products, DS2778 Datasheet

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... The DS2775–DS2778 operate from +4.0V to +9.2V for direct integration into battery packs with two Li+ or Li- Poly cells. In addition to nonvolatile storage for cell compensation and application parameters, the DS2775– ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication ABSOLUTE MAXIMUM RATINGS Voltage Range on PLS, CP, CC, DC Pins Relative to V .....................................................-0.3V to +18V SS Voltage Range SRC Pins ...

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... DQ, PIO, SDA Output Logic-Low DQ, PIO Pullup Current DQ, PIO, SDA, SCL Pulldown Current DQ Input Capacitance DQ Sleep Timeout t PIO, DQ Wake Debounce SHA-1 COMPUTATION TIMING (DS2776/DS2778 ONLY +4.0V to +9.2V 0°C to +70°C, unless otherwise noted. Typical values are PARAMETER SYMBOL Computation Time ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication EEPROM RELIABILITY SPECIFICATION (V = +4.0V to +9.2V -20°C to +70°C, unless otherwise noted PARAMETER SYMBOL EEPROM Copy Time EEPROM Copy Endurance ELECTRICAL CHARACTERISTICS: 1-Wire ...

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... Note 3: Overvoltage (OV) and undervoltage (UV) delays (t detected within 100ms of entering active mode. Note 4: Timing must be fast enough to prevent the DS2777/DS2778 from entering sleep mode due to bus low for period > t Note 5: f must meet the minimum clock low time plus the rise/fall times. ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication (T = +25°C, unless otherwise noted.) A DISCHARGE-OVERCURRENT PROTECTION DELAY 2V/div 0V 2V/div 0V 1V/div 0V 20mV/div TIME (ms) DC ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication (T = +25°C, unless otherwise noted.) A CURRENT MEASUREMENT ACCURACY 125 75 -20°C +25°C 25 -25 +70°C -75 -125 -0.052 -0.032 -0.012 0.008 0.028 0.048 V (mV) SNS _______________________________________________________________________________________ ...

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... Charge Pump Output. Generates gate drive voltage for protection FETs. Bypass with 0.47μF to SRC. — EP Exposed Pad. Connect to ground or no connection. 8 _______________________________________________________________________________________ TOP VIEW DS2775 DS2776 V 4 IN2 DS2777 V 5 IN1 DS2778 TDFN-EP × (3mm 5mm) FUNCTION . SS SS www.DataSheet4U.com Pin Configuration SRC 12 SCL/OVD 11 ...

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... USER REGULATOR VB VB INTERNAL _______________________________________________________________________________________ VOLTAGE CONTROL TEMPERATURE CURRENT PRECISION ANALOG FuelPack™ OSCILLATOR PIO LOGIC 32-BYTE EEPROM COMMUNICATION INTERFACE EEPROM DS2775–DS2778 www.DataSheet4U.com Block Diagram V IN2 10-BIT + SIGN ADC/MUX V IN1 SNS 15-BIT + SIGN ADC VREF V SS PIN SDA/DQ DRIVERS ...

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... DS2775/DS2776 Typical Application Circuit 1kΩ 1kΩ 1kΩ CC SRC DC PLS IN2 V DS2775 IN1 DS2776 PIO CP VB SNS V OVD SS SRC R SNS DS2777/DS2778 Typical Application Circuit 1kΩ 1kΩ 1kΩ CC SRC DC PLS V DD SDA V IN2 SCL V DS2777 IN1 DS2778 PIO CP VB SNS V SS 0.1μF R SNS www.DataSheet4U.com 150Ω ...

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... Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Detailed Description The DS2775–DS2778 function as an accurate fuel gauge, Li+ protector, and SHA-1-based authentication token (SHA-1-based authentication available only on the DS2776/DS2778). The fuel gauge provides accu- rate estimates of remaining capacity and reports timely voltage, temperature, and current measurement data ...

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... FET. The DC out- put remains high during overvoltage to allow discharging. When (V below the charge-enable threshold, V DS2775–DS2778 turn the charge FET on by driving CC high. The DS2775–DS2778 drive CC high before [( and (V ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Table 1. Li+ Protection Conditions and DS2775/DS2776 Responses CONDITION THRESHOLD Overvoltage (OV) (Note 1) V CELL Undervoltage (UV) (Note 1) V CELL Overcurrent, Charge (COC) V SNS Overcurrent, Discharge ...

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... for a period longer than undervoltage delay the DS2775–DS2778 shut off the charge and discharge FETs. If UVEN is set, the DS2775–DS2778 also enter sleep mode. When a charger is detected and the DS2775–DS2778 provide a current-limited IN2 recovery charge path (I ...

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... Temperature measurements are updated every 440ms and placed in the Temperature register in two’s complement form. Current Measurement In active mode, the DS2775–DS2778 continuously mea- sure the current flow into and out of the battery by mea- suring the voltage drop across a low-value current-sense resistor, R ...

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... NBEN bit in the Control register. See the Control Register Format description for additional information. The DS2775–DS2778’s current measurement gain can be adjusted through the RSGAIN register, which is facto- ry calibrated to meet the data sheet specified accuracy. ...

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... The 16-bit FRSGAIN value is readable from addresses B0h and B1h. Sense-Resistor Temperature Compensation The DS2775–DS2778 can temperature compensate the current-sense resistor to correct for variation in a sense resistor’s value over temperature. The DS2775–DS2778 are factory programmed with the sense-resistor temper- ature coefficient, RSTC, set to zero, which turns off the temperature compensation function ...

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... Gauging with Maxim Battery Monitor ICs. To facilitate efficient implementation in hardware, a modified version of the method outlined in Application Note 131 is used to store cell characteristics in the DS2775–DS2778. Full and empty points are retrieved in a lookup process that retraces a piecewise linear model consisting of three model curves named full, active empty, and standby empty ...

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... The application’s charge termination method should be used to determine the table values. The DS2775–DS2778 reconstruct the full line from cell char- acteristic table values to determine the full capacity of the battery at each temperature. Reconstruction occurs in one-degree temperature increments ...

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... IN2 standby-load current and voltage are used for deter- mining the cell characteristics but are not programmed into the DS2775–DS2778. The DS2775–DS2778 recon- struct the standby-empty line from the cell characteris- tic table to determine the standby-empty capacity of the battery at each temperature. Reconstruction occurs Standby Empty in one-degree temperature increments ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication -10 full with a resolution Standby empty at +40°C is, by definition, zero and therefore no storage is required. The slopes (derivatives) of the four segments ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Minimum Charge Current (IMIN) IMIN stores the charge-current threshold used to detect a fully charged state stored as a 1-byte value with units of 50µV (IMIN x ...

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... Note: Do not confuse the active-empty point with the active-empty flag. The active-empty flag is set only when the VAE threshold is passed. The DS2775–DS2778 process measurement and cell characteristics on a 3.5s interval and yield seven result registers. The result registers are sufficient for direct display to the user in most applications ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication MSB—ADDRESS 02h MSb Figure 16. Remaining Active Absolute Capacity (RAAC) [mAh] The RAAC register reports the capacity available under ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The Protection register reports events detected by the Li+ safety circuit on bits [7:2]. Bits 0 and 1 are used to disable the charge and discharge FET gate drivers. ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The Status register contains bits that report the device status. All bits are set internally. The CHGTF, AEF, SEF, and LEARNF bits are read-only. BIT 7 BIT 6 BIT ...

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... V and V IN1 disables transitions to sleep mode during an undervoltage condition. Bit 5: Power-Mode Enable (PMOD). A value of 1 allows the DS2775–DS2778 to enter sleep mode when DQ is low for value of 0 disables DQ-related transitions to sleep mode. SLEEP Bit 4: Read Net Address Op Code (RNAOP). A value of 0 selects 33h as the op code value for the Read Net Address command ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The 8-bit Overvoltage Threshold register (VOV) sets the overvoltage threshold for the protection circuitry. An over- voltage condition is detected if either of the voltages on V the VOV ...

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... X Bits Reserved. Bit 1: SHA Idle Bit (SHA_IDLE). For the DS2777/DS2778, this bit reads logic 1 while an SHA calculation is in progress and reads logic 0 when the calculation is complete. Bit 0: PIO Pin Sense and Control Bit (PIOB). Writing the PIOB bit activates the PIO pin open-drain output driver, forcing the PIO pin low ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The EEPROM register provides access control of the EEPROM blocks. EEPROM blocks can be locked to prevent alteration of data within the block. Locking a block disables write access ...

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... Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication The DS2775–DS2778 have a 256-byte linear memory space with registers for instrumentation, status, and control, as well as EEPROM memory blocks to store parameters and user information. Byte addresses des- ignated as “reserved” typically return FFh when read. ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Table 8. Parameter EEPROM Memory Block ADDRESS DESCRIPTION (HEX) 60h Control Register 61h Accumulation Bias Register (AB) 62h Aging Capacity Register MSB (AC) 63h Aging Capacity Register LSB (AC) ...

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... Contact Maxim for details of the message block organization. The host and the DS2776/DS2778 both calculate the result based on the mutually known secret. The result data, known as the message authentication code (MAC) or message digest, is returned by the DS2776/DS2778 for comparison to the host’ ...

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... MAC’s 64 bits are used as the new secret value. The host must allow t the SHA calculation to complete, then wait t DS2776/DS2778 to write the new secret value to EEPROM. See Figure 26 for command timing. Compute Next Secret with ROM ID [33h] This command initiates an SHA-1 computation of the MAC and uses a portion of the resulting MAC as the next or new secret ...

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... This command write protects the 64-bit secret to pre- vent accidental or malicious overwrite of the secret value. The secret value stored in EEPROM becomes "final." The host must wait t for the DS2776/DS2778 EEC to write the lock secret bit to EEPROM. See Figure 28 for command timing. ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication also used to provide verification of error-free data trans- fer as each EEPROM page is sent to the master during a Read Data/Generate CRC command and for the 8 ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication Match Net Address [55h] This command allows the bus master to specifically address one DS2775/DS2776 on the 1-Wire bus. Only the addressed DS2775/DS2776 responds to any sub- sequent function ...

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... Generates new unique secret. 39h Returns the ROM ID (DS2778 only). 3Ah Returns the 160-bit MAC (DS2778 only). 60h Sets lock bit to prevent changes to the secret. 69h, XXh Reads data from memory starting at address XXh. 6Ch, XXh Writes data to memory starting at address XXh. ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication 1-Wire SKIP-ROM RESET COMMAND PRESENCE COMPUTE PULSE MAC COMMAND Figure 25. Compute MAC Command 1-Wire SKIP-ROM RESET COMMAND PRESENCE COMPUTE PULSE NEXT SECRET COMMAND Figure 26. Compute Next Secret ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication 1-Wire SKIP-ROM RESET COMMAND PRESENCE PULSE Figure 28. Clear/Lock Secret, Set/Clear Overdrive Commands DQ LINE TYPE LEGEND: Figure 29. 1-Wire Initialization Sequence 1-Wire Signaling The 1-Wire bus requires strict ...

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... The DS2777/DS2778’s SDA pin operates bidi- rectionally, that is, when the DS2777/DS2778 receive data, SDA operates as an input, and when the DS2777/DS2778 return data, SDA operates as an open- drain output with the host system providing a resistive pullup. The DS2777/DS2778 always operate as a slave ...

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Stand-Alone, Li+ Fuel-Gauge IC with Protector and Optional SHA-1 Authentication V PULLUP GND MIN MODE: 15μs 15μs STANDARD 2μs OVERDRIVE t RDV V PULLUP GND MODE: 15μs STANDARD 2μs OVERDRIVE LINE TYPE LEGEND: Figure 30. 1-Wire Write and Read ...

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... R BIT 7 BIT 6 BIT Bits Slave Address (A[6:0]). A[6:0] contains the 7-bit slave address of the DS2777/DS2778. The factory default is 1011001b. Bit 0: Reserved. ______________________________________________________________________________________ Data Order selects a read transaction, with the subsequent bytes being read from the slave by the master. ...

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... EEPROM blocks, as well as a write that auto-increments to the Function Command register (address FEh). Incomplete bytes and bytes that are not acknowledged by the DS2777/DS2778 are not written to memory. As noted in the Memory section, writes to unlocked EEPROM blocks modify the shadow RAM only. 44 ...

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... DS2777G+ 2-Wire DS2777G+T&R 2-Wire DS2778G+ 2-Wire DS2778G+T&R 2-Wire + Denotes a lead(Pb)-free/RoHS-compliant package. T&R = Tape and reel. ______________________________________________________________________________________ DESCRIPTION This command copies the shadow RAM to the target EEPROM block. Copy data commands that target locked blocks are ignored. While the Copy Data command is executing, the EEC bit in the EEPROM register is set to 1, and write data commands with MAddr set to any address within the target block are ignored ...

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... Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 46 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2010 Maxim Integrated Products DESCRIPTION Maxim is a registered trademark of Maxim Integrated Products, Inc ...